A typical gas turbine includes an inlet section, a compressor section, a combustion section, a turbine section, and an exhaust section. The inlet section cleans and conditions a working fluid (e.g., air) and supplies the working fluid to the compressor section. The compressor section progressively increases the pressure of the working fluid and supplies a compressed working fluid to the combustion section. The compressed working fluid is mixed with a fuel such as natural gas to provide a combustible mixture.
The combustible mixture is injected into a combustion zone defined within a combustion chamber where it is burned to generate combustion gases having a high temperature and pressure. The combustion gases are routed through a hot gas path that is defined within the combustor into the turbine section. Thermal and kinetic energy is transferred from the combustion gases to successive stages of turbine rotor blades that are coupled to a rotor wheel or disk that is coupled to a shaft, thereby causing the shaft to rotate and produce work. For example, the shaft may drive a generator to produce electricity.
Turbine rotor blades typically include an airfoil portion, a mounting or root portion and a hollow base or shank portion that extends radially between the root portion and the airfoil portion. The mounting portion generally includes a dovetail feature for securing the turbine rotor blade to the rotor disk. A generally rectangular platform portion is disposed between the shank and the airfoil. The platform generally includes a bottom or cold side and a top or hot side where the hot side is directly exposed to the hot combustion gases. The airfoil extends generally radially outward from the hot side of the platform.
High combustion gas temperatures within the turbine section generally corresponds to greater thermal and kinetic energy transfer between the combustion gases and the turbine rotor blades, thereby enhancing overall power output of the gas turbine. However, the high combustion gas temperatures may lead to erosion, creep, and/or low cycle fatigue to the turbine rotor blades, thereby limiting durability of the turbine rotor blades. Therefore, continued improvements in turbine rotor blade cooling schemes and methods for cooling the turbine rotor blade would be useful.